chore: cascade forgejo pull request out of the runner branch or PR

Refs forgejo/runner#881

.forgejo/cascading-forgejo

@@ -0,0 +1,37 @@
+#!/bin/bash
+
+set -ex
+
+forgejo=$1
+forgejo_pr=$2
+runner=$3
+runner_pr_or_ref=$4
+
+#
+# Get information from the runner
+#
+cd $runner
+#
+# code.forgejo.org/forgejo/runner/vN may be
+# upgraded to code.forgejo.org/forgejo/runner/vN+1
+#
+module=$(cat go.mod | head -1 | cut -d' ' -f2)
+test "$module"
+sha=$(git -C $runner show --no-patch --format=%H)
+test "$sha"
+
+#
+# Update Forgejo to use the runner at $runner_pr_or_ref
+#
+cd $forgejo
+#
+# Update the runner major version if needed
+#
+find * -name '*.go' -o -name 'go.mod' | xargs sed -i -E -e "s|code.forgejo.org/forgejo/runner/v[0-9]+|$module|"
+#
+# add a "replace code.forgejo.org/forgejo/runner/v?? $sha" line to the forgejo go.mod
+# so that it uses the branch or pull request from which the cascade is run.
+#
+sed -i -e "\|replace $module|d" go.mod
+echo "replace $module => $module $sha" >>go.mod
+go mod tidy

.forgejo/workflows/cascade-forgejo.yml

@@ -0,0 +1,88 @@
+# Copyright 2025 The Forgejo Authors
+# SPDX-License-Identifier: MIT
+#
+# FORGEJO_CASCADING_PR_ORIGIN_TOKEN is a token from the https://code.forgejo.org/cascading-pr user
+# with scope write:issue read:repository read:user
+# FORGEJO_CASCADING_PR_DESTINATION_TOKEN is a token from the https://codeberg.org/forgejo-cascading-pr user
+# with scope write:issue write:repository read:user
+#
+# To modify this workflow:
+#
+#  - push it to the wip-cascade branch on the repository
+#    otherwise it will not have access to the secrets required to push
+#    the cascading PR
+#
+#  - once it works, open a pull request for the sake of keeping track
+#    of the change even if the PR won't run it because it will use
+#    whatever is in the default branch instead
+#
+#  - after it is merged, double check it works by setting the
+#    label on a pull request (any pull request will do)
+#
+name: cascade
+
+on:
+  push:
+    branches:
+      - 'main'
+      - 'wip-cascade'
+  pull_request_target:
+    types:
+      - synchronize
+      - labeled
+
+enable-email-notifications: true
+
+jobs:
+  debug:
+    if: >
+      vars.DEBUG == 'yes'
+    runs-on: docker
+    container:
+      image: data.forgejo.org/oci/node:22-bookworm
+    steps:
+      - name: event
+        run: |
+          cat <<'EOF'
+          ${{ toJSON(forge.event.pull_request.labels.*.name) }}
+          EOF
+          cat <<'EOF'
+          ${{ toJSON(forge.event) }}
+          EOF
+
+  forgejo:
+    if: >
+      vars.ROLE == 'forgejo-coding' && (
+        forge.ref_name == 'main' ||
+        forge.ref_name == 'wip-cascade' ||
+        contains(github.event.pull_request.labels.*.name, 'run-forgejo-tests')
+      )
+
+    runs-on: docker
+    container:
+      image: data.forgejo.org/oci/node:22-bookworm
+    steps:
+      - uses: https://data.forgejo.org/actions/checkout@v4
+        with:
+          fetch-depth: '0'
+          show-progress: 'false'
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+      - uses: https://data.forgejo.org/actions/cascading-pr@v2.2.1
+        with:
+          origin-url: ${{ forge.server_url }}
+          origin-repo: ${{ forge.repository }}
+          origin-token: ${{ secrets.FORGEJO_CASCADING_PR_ORIGIN_TOKEN }}
+          origin-pr: ${{ forge.event.pull_request.number }}
+          origin-ref: ${{ forge.event_name == 'push' && forge.event.ref || '' }}
+          destination-url: https://codeberg.org
+          destination-fork-repo: forgejo-cascading-pr/forgejo
+          destination-repo: forgejo/forgejo
+          destination-branch: forgejo
+          destination-token: ${{ secrets.FORGEJO_CASCADING_PR_DESTINATION_TOKEN }}
+          prefix: runner
+          close-merge: true
+          verbose: ${{ vars.VERBOSE == 'yes' }}
+          debug: ${{ vars.DEBUG == 'yes' }}
+          update: .forgejo/cascading-forgejo